Temperature gauge goes all the way around

So, not only does my temperature gauge go all the way around, but it keeps saying “Engine Hot A/C Off” even if it’s sat for weeks. The fan will run high, and intermittently work properly. The gauge doesn’t always say cold or hot, it can actually point to the 3 o’clock position, and have the same issue.
In the 4.5 years I’ve owned this lease-buy-back, the ECT and thermostat have been replaced 3 times each. It’s not actually overheating, but thinks it is. There are no leaks, and the coolant is fine.
I live in Alberta Canada, and I’m on permanent disability (AISH) so I have very limited money, as well as I am so not mechanically inclined at all.
I have an App which has a OBD type device, called Telus Drive, that gives you certain information on the car (gas mileage, parking location, geofencing, as well as diagnostic codes), and the code it’s saying is a Thermostat Coolant Malfunction. I’m not entirely certain this could be the issue.
Any suggestions?